refactor: set default aur helper to constant

src/caelestia/utils/dots/state.py

@@ -1,6 +1,7 @@
 import json
 from dataclasses import dataclass, field
 
+from caelestia.utils.dots.packages import DEFAULT_AUR_HELPER
 from caelestia.utils.io import warn
 from caelestia.utils.paths import atomic_dump, dots_state_path
 
@@ -31,7 +32,7 @@ class DotsState:
             return DotsState()
 
         return DotsState(
-            aur_helper=data.get("aur_helper"),
+            aur_helper=data.get("aur_helper", DEFAULT_AUR_HELPER),
             applied_rev=data.get("applied_rev"),
             enabled_components=data.get("enabled_components", []),
             packages=data.get("packages", []),